bhyve, sparse disk image and trim support?

[Bjoern A. Zeeb]

Hi,

I have been wondering about this with other (commercial) virtualisation 
solutions in the past.  If running on a “disk image” ideally I’d 
love that image to be a sparse file and ideally I’d love for 
bhyve/underlying virtualisation for the disk to understand TRIM so in 
case one deletes huge junks inside the VM the disk image can actually 
shrink again.

Examples might be: you do a buildworld or an OS update in the guest and 
then want to delete the obj tree or temporary files after that.  Now the 
disk image on the host has been bloated up, and could massively shrink 
again saving space on the host.

Do we support this?  Has anyone worked on this?  How do people deal with 
these problems?


/bz